1. Field of the Invention
The present invention relates to engine control modules, and in particular, to recreating valid calibration data when a non-volatile memory failure has occurred, for example, due to worn out memory locations.
2. Background Art
Engine control modules typically include volatile memory and non-volatile memory for storing calibration data. A microprocessor within the engine control module executes the stored calibration data to control an engine.
In operation, the non-volatile memory are copies typically used as back ups to the volatile memory copy. When needed, the calibration data values stored in the non-volatile memory can be copied to the volatile. A user can make changes to the calibration data in volatile memory, however, the user cannot typically change the non-volatile memory directly.
In the past, changes to the volatile memory calibration data prompted the engine control module to copy the entire volatile memory to the non-volatile memory. The engine control module would then verify the copied data, and if valid, another copy of the data would be made to a second non-volatile memory area. If not valid, implying that the first volatile memory may be faulty or power was removed during the copy process, etc., the data stored in the second non-volatile memory can be used to restore the volatile memory calibration data in order to maintain functionality. In this manner, a verified copy of the calibration data is available even if one of the non-volatile copies are invalid.
The copying of the calibration data causes repeated writing to the memories. Eventually, the memory will fatigue and fail. This is a problem. As such, there exists a need to provide a means to recreate valid data even if portions of the non-volatile memory fails.
In addition to memory wear-out problems, engine control modules are becoming more complex and require larger memories. The increased memory demand increases costs. This is also a problem. As such, there exists a need to limit memory while providing the necessary back-up protection in a cost effective manner.